STUDY OF THE PHYSICAL, MECHANICAL, CHEMICAL AND THERMAL CHARACTERISTICS OF PHENOLIC RESIN-STEEL SLAG REINFORCED COMPOSITES
This study investigated the characteristics of non-asbestos brake pads in hybrid-polymer matrix composites. Steel slag, silica, calcium tri-oxocarbonate IV and graphite in varied weight percentages were added to the molten phenolic resin to develop the composites. The microstructural examination was carried out on the samples using a scanning electron microscope. The composites’ physical, mechanical, chemical and thermal properties were evaluated at room temperature. The results obtained were compared with a commercial brake pad. The microstructure revealed a fair distribution of the particles in the resin matrix. The control sample exhibited the lowest wear rate of 0.6 and 0.8 g/Nm at loads of 7.5 and 10 N, respectively. This implies better wear resistance characteristics than the other samples. The samples exhibited appreciably high coefcient of friction of 0.410, 0.413, 0.440 and 0.40 for samples A, B, C and D, respectively, which is within the acceptable limit (0.3 – 0.6) for the brake pad. Sample A exhibited the highest compressive strength of 7.78 MPa, which is followed by samples C (3.04 MPa) and D (1.52 MPa). The results indicate that the compressibility of samples decreased with increasing steel slag and phenolic resin content. Sample D, which exhibited a lower wear rate (1 g/Nm) and coefcient of friction (0.40) than samples A, B, and C, exhibited the lowest water absorption rate. The specifc gravity of the samples produced ranges between 2.45 and 2.61, which compare well with the commercial brake pad. Sample A was produced with the lowest proportion of steel slag and phenolic resin and exhibited the lowest acetone extraction. Samples A and B exhibited better thermal stability – an indication of good resistance to thermal decomposition. The thermal conductivity of the samples ranges between 134 and 193 W/mK, which is quite high compared to the standard and decreased signifcantly with an increase in temperature.
Keywords: Hybrid polymer composites, steel slag, wear rate, coefcient of friction, compressive strength, thermal stability.
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